Modern telecommunication systems include heterogeneous mixtures of second, third, and fourth generation (2G, 3G, and 4G) cellular-wireless access technologies, which can be cross-compatible and can operate collectively to provide data communication services. Global Systems for Mobile (GSM) is an example of 2G telecommunications technologies; Universal Mobile Telecommunications System (UMTS) is an example of 3G telecommunications technologies; and Long Term Evolution (LTE), including LTE Advanced, and Evolved High-Speed Packet Access (HSPA+) are examples of 4G telecommunications technologies.
In addition, a new generation of portable communication devices, or user equipment (UE), are capable of making phone calls over a wireless local area network (WLAN), referred as Wi-Fi™ calling or WFC. To be able to make or receive a call through a WLAN, the WFC UE first registers its Internet Protocol (IP) address with the WLAN. When the WFC UE makes a Wi-Fi emergency call, the IP address that the UE used to register is provided to a 911 communication center known as a Public Safety Answering Point (PSAP). However, unlike a traditional geographical address, the IP address of the UE may not provide a physical location of the UE, which may be crucial.